WO2024083048A1

WO2024083048A1 - Catalyst for preparing methyl acetate from dimethyl ether and/or methanol by means of carbonylation and use thereof

Info

Publication number: WO2024083048A1
Application number: PCT/CN2023/124541
Authority: WO
Inventors: 高裕一; 杨国辉; 椿大輝
Original assignee: 高化学株式会社; 株式会社模范; 高裕一
Priority date: 2022-10-17
Filing date: 2023-10-13
Publication date: 2024-04-25
Also published as: CN117920322A

Abstract

The present invention relates to a catalyst for preparing methyl acetate from dimethyl ether and/or methanol by means of carbonylation. The catalyst comprises a first catalyst layer which contains a metal loaded on a carrier material and a second catalyst layer which contains an H-type molecular sieve, wherein the first catalyst layer and the second catalyst layer are spatially separated. The catalyst of the present invention can obviously improve the yield of methyl acetate and has a considerable selectivity. In addition, the present invention further relates to a method for preparing methyl acetate from dimethyl ether and/or methanol by means of carbonylation using the catalyst.

Description

Catalyst for preparing methyl acetate by carbonylation of dimethyl ether and/or methanol and its use

Technical Field

The present invention relates to a catalyst, in particular to a catalyst for preparing methyl acetate by carbonylation of dimethyl ether and/or methanol; and a method for preparing methyl acetate by carbonylation of dimethyl ether and/or methanol using the catalyst.

Background technique

Methyl acetate is widely used in the fragrance, coating, adhesive and pharmaceutical industries. It is not only a good environmentally friendly solvent that can be used to replace acetone, butanone, ethyl acetate, cyclopentane, etc., but also an important organic raw material intermediate. Its downstream products mainly include acetic acid, ethanol, acetic anhydride, methyl acrylate, vinyl acetate, acetamide, etc. The demand for methyl acetate at home and abroad is increasing. In recent years, methyl acetate has developed some new applications, such as hydrogenation synthesis of ethanol.

Industrially, methyl acetate is usually prepared from dimethyl ether and/or methanol by carbonylation reaction.

The conventional production process of carbonylation of dimethyl ether and/or methanol to produce methyl acetate mostly adopts homogeneous catalysis. However, this method has the problem of difficulty in separating the product from the catalyst; in addition, the use of precious metals increases the production cost; and the use of iodides causes great corrosion to the equipment and is not conducive to the operating environment. Wegman et al. (J Chem Soc Chem Comm 1994, (8), 947-948) developed a dimethyl ether carbonylation reaction using heteropoly acid RhW ₁₂ PO ₄ /SiO ₂ as a catalyst, and obtained a 16% yield of methyl acetate. Volkova et al. (Catalyst Letters 2002, 80 (3-4), 175-179) used Rh/CsxH ₃ -xPW ₁₂ O ₄₀ to study the carbonylation reaction of dimethyl ether, and obtained a reaction rate one order of magnitude higher than that of RhW ₁₂ P (VSiO ₂ ). However, the above catalyst systems all use precious metals, thereby increasing the cost of producing methyl acetate. In addition, these catalyst systems tend to generate a large amount of hydrocarbons and carbon deposits during the dimethyl ether carbonylation reaction, so that the production of methyl acetate requires frequent shutdowns to replace the catalyst.

In 2006, Iglesia et al. (Angew. Chem, Int. Ed., 2006, (10), 1617-1620) reported that mordenite (MOR) and ZSM-35 molecular sieves have good dimethyl ether carbonylation activity. Since molecular sieves do not need to load precious metals and are easy to regenerate, the cost of preparing methyl acetate or acetic acid is effectively reduced, making molecular sieve catalysts a popular catalyst for studying the carbonylation of dimethyl ether to prepare acetic acid. Hot spots for methyl esters.

A great deal of research work has focused on the effects of zeolite topology, acid strength and density, morphology control and metal modification on the performance of dimethyl ether carbonylation catalysts.

In the research work on the carbonylation reaction of metal-modified MOR, the acid sites of the molecular sieve are increased and the distribution of the acid sites is regulated by introducing metal elements or loading a certain amount of metal elements, so as to achieve the purpose of improving the activity of the molecular sieve in catalyzing the carbonylation of dimethyl ether. So far, the mainstream mechanism in the carbonylation of dimethyl ether believes that the activation of CO or dimethyl ether/methanol requires the assistance of the metal functional sites of the molecular sieve and the Bronsted acid sites of the molecular sieve. Because Weisz's intimacy criterion believes that the shorter the distance between the metal active site and the acid active site, the more it can promote the communication between them, that is, "the closer the better". Most related work has also proved that the catalytic performance of bifunctional catalysts can be improved by adjusting and shortening the distance between the two active sites at the nanoscale.

However, MOR after metal ion exchange has problems such as unstable skeleton and easy internal metal aggregation, and the space-time yield and selectivity of the product methyl acetate still need to be improved. In addition, molecular sieves loaded with metals by impregnation method also have similar problems.

Therefore, there is a need in the art for a catalyst for preparing methyl acetate by carbonylation of dimethyl ether, which can significantly improve the space-time yield of methyl acetate and has considerable selectivity.

Summary of the invention

In view of the above-mentioned state of the prior art, the inventors have conducted extensive and in-depth research on molecular sieve catalysts for preparing methyl acetate and/or acetic acid by carbonylation of dimethyl ether and/or methanol, in order to discover a catalyst with a completely new structure having stable carbonylation activity. The inventors have found that by isolating the metal from the molecular sieve in space, the space-time yield of methyl acetate can be significantly improved, and the selectivity is considerable. Considering the general understanding of the art described above, that is, the closer the distance between the metal active site and the acid active site, the better, the discovery of the present invention - that is, isolating the metal from the molecular sieve in space can significantly improve the space-time yield of methyl acetate and have considerable selectivity - is surprising and unexpected.

Therefore, in a first aspect of the present invention, the present invention relates to a catalyst comprising a first catalyst layer comprising a metal supported on a support material and a second catalyst layer comprising an H-type molecular sieve, wherein the first catalyst layer and the second catalyst layer are spatially isolated.

The metal in the first catalyst layer may be those metals in the metal-modified MOR commonly used in the art for carbonylation reactions, such as one or more of Ca, Ag, Ce, Pt, Pd, Ga, Zn, Mg, Au, Co, Fe, Zr, Ni or Cu, preferably one or more of Cu, Pd, Ag, Ce, Co, Ga, Zr, Zn or Fe, most preferably one or both of Cu or Pd.

The support material in the first catalyst layer may be a conventional inert support, such as silica, zirconia, titania, ceria, activated carbon, graphene, carbon nanotubes or a combination thereof, preferably silica, activated carbon, graphene, carbon nanotubes or a combination thereof.

The metal loading of the support material in the first catalyst layer can be 0.001 to 30% by weight, preferably 0.01 to 25% by weight, more preferably 0.1 to 20% by weight, most preferably 0.5 to 15% by weight, in each case based on the total weight of metal and support material in the first catalyst layer.

The specific surface area of the metal-loaded support material in the first catalyst layer can be 300-700 m ² /g, preferably 400-600 m ² /g, in each case determined by mercury porosimetry using N _2. Surprisingly, it has been found that when the specific surface area of the support material is within the above range, the resulting catalyst has a high space-time yield and selectivity.

The pore volume of the metal-loaded support material in the first catalyst layer can be 0.10-1.50 mL/g, preferably 0.20-0.70 mL/g, in each case determined according to the nitrogen adsorption-desorption BET method. Surprisingly, it has been found that when the pore volume of the support material is within the above range, the resulting catalyst has a high space-time yield and selectivity.

The pore size of the metal-loaded support material in the first catalyst layer may be 3.0-50.0 nm, preferably 7.0-10 nm.

The particle size of the support material may be 10-10000 μm, preferably 20-5000 μm, more preferably 40-1000 μm, more preferably 50-500 μm, most preferably 60-250 μm.

The loading of the metal on the support material can be achieved by methods known in the art, such as impregnation, in particular incipient wetness impregnation. Incipient wetness impregnation, also known as capillary impregnation or dry impregnation, is commonly used to synthesize heterogeneous materials, i.e., catalysts. Typically, the precursor is dissolved in water or an organic solvent and the resulting solution is added to a catalyst support having a pore volume approximately the same as the volume of solution added. Capillary action draws the solution into the support pores. The catalyst can then be dried and calcined to remove volatile components to deposit the metal on the support material.

Prior to impregnation, the support material may be subjected to a vacuum degassing treatment. The treatment is carried out at a temperature of 80-150° C., and the treatment time may be 0.5-10 hours. Then, the vacuum degassed support is immersed in a solution of a soluble salt of the metal. The soluble salt may be a nitrate, a sulfate, a carboxylate or a halide, especially a chloride. For example, for copper, its soluble salt may be copper nitrate, copper sulfate, copper acetate, copper oxalate or a copper halide, wherein the copper halide may be selected from copper chloride or copper bromide, including hydrate and non-hydrate forms. Preferably, the water-soluble copper salt is copper nitrate, copper sulfate or copper chloride. In addition, copper complexes, such as copper ammonia complexes, may also be used.

During the impregnation process, the support material can be stirred to ensure uniform metal loading. The stirring can be performed with a stirrer or ultrasound assistance, preferably ultrasound assistance.

After impregnation, the resulting wet solid can be vacuum degassed, then dried, and finally calcined. Vacuum degassing can be carried out at a temperature of 80-150°C, and the treatment time can be 0.5-72 hours, preferably 10-50 hours. Drying can be carried out at a temperature of 80-150°C, and the drying time can be 0.5-24 hours. Calcination can be carried out at a temperature of 200-700°C, preferably 300-600°C, and the calcination time can be 0.5-24 hours.

The H-type molecular sieve in the second catalyst layer can be H-type ZSM-34, ZSM-35, MOR, CHA, OFF, EU-12, Al-RUB-41 or HSUZ-4, preferably H-type OFF, EU-12, Al-RUB-41, ZSM-34 or MOR, and more preferably H-type MOR (H-MOR).

The H-type molecular sieve can be commercially available or prepared by a method known in the art, such as a solvent thermal method, preferably a hydrothermal method. The hydrothermal method comprises the following steps: mixing an aluminum source, a silicon source, an alkali source, an optional template agent and water, and performing a hydrothermal crystallization reaction to obtain a crystallization reaction material; drying the crystallization reaction material, then calcining it, and finally reducing it to obtain the H-type molecular sieve.

The aluminum source can be selected from one or more of sodium aluminate, aluminum nitrate, aluminum isopropoxide, and aluminum chloride; the alkali source can be selected from one or more of sodium hydroxide, sodium carbonate, and potassium hydroxide; the silicon source can be selected from one or more of silicon dioxide, silica sol, water glass, and organic silane; when used, the template can be selected from one or more of choline chloride, tetraethylammonium hydroxide, and tetramethylammonium chloride.

The amounts of the aluminum source, alkali source, silicon source, optional template agent (SDA) and water are known in the art. For example, when preparing H-MOR, the molar ratio may be n( _Al2O3 ):n( _Na2O ):n( _K2O ):n( _SiO2 ):n( _H2O ):n( _SDA )=1:(2.5-5.1):(0.76-9.13):(10.54-30):(130-216):(0-1.3).

The hydrothermal crystallization can be carried out in a closed container (e.g., autoclave) under the autogenous pressure of the reaction system. The crystallization temperature can range from 100-300°C, preferably 150-300°C; the crystallization time can range from 1 hour to 10 days, preferably 4 hours to 5 days.

During the hydrothermal crystallization, a slow-release agent may be added. Suitable slow-release agents include, but are not limited to, urea, ammonium acetate, ammonium oxalate or ammonium carbonate. The amount of the slow-release agent may be 0-2.0% by weight, preferably 0.01-1.5% by weight, and more preferably 0.1-1.0% by weight, based on the total weight of the reaction mixture.

After the reaction, the reaction mixture can be filtered and washed with distilled water several times (e.g., 1-10 times, preferably 1-3 times) until the washing liquid is neutral. Then, the filtrate is dried. Drying can be carried out by various drying methods known in the prior art, such as ordinary heating drying, microwave drying and/or spray drying. In the case of heating drying, the drying temperature can be 50-200° C., preferably 80-150° C., and the drying time can be 1-24 hours, more preferably 4-20 hours, more preferably 8-15 hours.

After drying, the resulting product can be shaped, and the shaping can be carried out in a manner known in the prior art, such as tableting, ball rolling or extrusion. The shaping can be carried out under the addition of a lubricant. The lubricant is, for example, graphite. The amount of lubricant used can be 1-10%, preferably 1-5%, based on the total weight of the lubricant and the dried product. After shaping, the resulting shaped body can be crushed and sieved through a 40-60 mesh sieve.

After screening, the obtained product is calcined. The calcination can be carried out in various ways known in the prior art, such as in a muffle furnace. The calcination temperature can be 300-800°C, preferably 350-600°C, more preferably 350-500°C; the calcination time can be 1-24 hours, preferably 1-12 hours, more preferably 1-5 hours.

In the catalyst of the present invention, the "first catalyst layer" and the "second catalyst layer" are relative to the flow direction of the reaction materials (such as dimethyl ether and CO, etc.), that is, relative to the flow direction of the reaction materials, the first catalyst layer is located upstream of the second catalyst layer.

In the catalyst of the present invention, "isolated in space" means that the first catalyst layer and the second catalyst are spatially separated by a macroscopically discernible distance, such as centimeter level, such as 0.5-100 cm, preferably 1-100 cm, more preferably 1-50 cm, more preferably 1-20 cm, most preferably 1-10 cm. The first catalyst layer and the second catalyst layer can be isolated by an inert material mesh, such as quartz wool, quartz sand, activated carbon, silicon dioxide, graphite, glass beads or ceramic rings.

The weight ratio of the first catalyst layer to the second catalyst layer may be 1:10 to 10:1, preferably 1:5 To 5:1, more preferably 1:2 to 2:1.

The catalyst of the invention can be used as a catalyst for preparing methyl acetate by carbonylation of dimethyl ether and/or methanol, and can significantly improve the space-time yield of methyl acetate and has considerable selectivity.

Therefore, in another aspect of the present invention, the present invention relates to a process for preparing methyl acetate by carbonylation of dimethyl ether and/or methanol, wherein the catalyst of the present invention is used.

According to the present invention, the carbonylation reaction can be carried out batchwise or continuously.

The catalyst of the present invention may be in any conventional form, preferably in the form of a fixed bed. In the carbonylation reaction, the reaction gas may be passed over the catalyst.

According to a preferred embodiment of the present invention, the carbonylation reaction temperature may be 180-330° C., preferably 200-280° C., for example 210-240° C., such as 220° C. or 230° C. The carbonylation reaction pressure may be 0.1-40 MPa, preferably 0.5-30 MPa. The gas flow rate of the carbonylation reaction may be 0.1-2000 mL/min, preferably 0.5-200 mL/min, more preferably 5-100 mL/min, and most preferably 10-50 mL/min.

According to the present invention, in the carbonylation reaction, CO is used in a molar excess relative to dimethyl ether and/or methanol. Preferably, the molar ratio of CO to dimethyl ether and/or methanol is 100:1-5:1, such as 80:1-8:1, 50:1-10:1, 40:1-12:1, 30:1-12:1, 20:1-14:1, more preferably 50:1-10:1, and even more preferably 25:1-12:1.

In one embodiment of the present invention, at least one inert gas, preferably argon, is used in the carbonylation reaction. When dimethyl ether and methanol are used as raw materials, the molar ratio of the reaction gas is Ar:DME:MeOH:CO=1:(0.1-20):(0.1-50):(1-50), preferably 1:(0.1-50):(0.1-50):(10-50). When dimethyl ether or methanol is used as a raw material, the molar ratio of the reaction gas is Ar:DME/MeOH:CO=1:(0.1-50):(1-50), preferably 1:(0.1-50):(10-50). Wherein DME is dimethyl ether and MeOH is methanol.

When methanol is used, the methanol can be passed into a gasification device for preheating and gasification. The gasification device can be a stainless steel tubular fixed bed reactor, which is filled with a material that does not have an adsorption function and has good thermal conductivity, preferably quartz sand or glass beads. The preheating gasification temperature is 70-400°C, preferably 80-300°C. The preheated methanol is then passed through a catalyst together with CO and an inert gas. When passing through the catalytic bed, the methanol is carbonylated to produce acetic acid, and the acetic acid is esterified with methanol to finally produce methyl acetate. Alternatively, methanol is first dehydrated to produce dimethyl ether, and dimethyl ether is carbonylated to produce methyl acetate.

Before the reaction, the catalyst of the present invention may be loaded into a reactor and then reduced. A hydrogen-containing gas may be used, such as pure _H2 or a mixture of _H2 and _N2 ( _H2 / _N2 ). In the case of using _H2 / _N2 , the volume content of _H2 may be 1-20%, more preferably 2-10%. The flow rate of the hydrogen-containing gas may be 5-500 ml/min, preferably 10-400 ml/min, more preferably 10-300 ml/min, and most preferably 80-200 ml/min. The reduction temperature may be 100-500°C, preferably 150-450°C, more preferably 200-400°C. The reduction time may be 0.5-50 hours, preferably 1-20 hours, and more preferably 2-10 hours.

The technical solution for achieving the purpose of the present invention can be summarized as follows:

1. A catalyst comprising a first catalyst layer comprising a metal supported on a support material and a second catalyst layer comprising an H-type molecular sieve, wherein the first catalyst layer and the second catalyst layer are spatially isolated.

2. A catalyst as described in Embodiment 1, wherein the metal in the first catalyst layer is one or more of Ca, Ag, Ce, Pt, Pd, Ga, Zn, Mg, Au, Co, Fe, Zr, Ni or Cu, preferably one or more of Cu, Pd, Ag, Ce, Co, Ga, Zr, Zn or Fe, most preferably one or more of Cu or Pd.

3. The catalyst as described in Embodiment 1 or 2, wherein the support material in the first catalyst layer is silica, zirconium oxide, titanium dioxide, cerium dioxide, activated carbon, graphene, carbon nanotubes or a combination thereof, preferably silica, activated carbon, graphene, carbon nanotubes or a combination thereof.

4. The catalyst as described in any one of embodiments 1-3, wherein the H-type molecular sieve is H-type ZSM-34, ZSM-35, MOR, CHA, OFF, EU-12, Al-RUB-41 or HSUZ-4, preferably H-type OFF, EU-12, Al-RUB-41, ZSM-34 or MOR, more preferably H-MOR.

5. A catalyst as described in any of embodiments 1-4, wherein the metal loading of the support material in the first catalyst layer is 0.001-30 wt.%, preferably 0.01-25 wt.%, more preferably 0.1-20 wt.%, and most preferably 0.5-15 wt.%, in each case based on the total weight of the metal and the support material.

6. The catalyst as described in any one of embodiments 1-5, wherein the first catalyst layer and the second catalyst are spatially separated by a distance of 0.5-100 cm, preferably 1-100 cm, more preferably 1-50 cm, more preferably 1-20 cm, and most preferably 1-10 cm.

7. A method for preparing methyl acetate by carbonylation of dimethyl ether and/or methanol, wherein the catalyst described in any one of embodiments 1 to 6 is used.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments, but they should not be construed as limiting the scope of protection of the present invention.

Example 1

Preparation of Cu/SiO ₂

Cu/ _SiO2 was prepared by incipient wetness impregnation. _SiO2 (CARiACT Q series, Q3, particle size 75-150 μm, pore volume 0.30 mL/g, specific surface area 550 ^m3 /g) obtained from Fujisilysia, Japan was used as the carrier, and the Cu source was Cu( _NO3 ) ₂ · _3H2O . 5 g of _SiO2 was vacuum degassed at 120°C for 6 hours, then placed in a glass beaker, and 10 mL of an aqueous solution containing 2.27 g of Cu( _NO3 ) ₂ · _3H2O was slowly impregnated into _SiO2 for 30 minutes under the assistance of ultrasound. During the impregnation process, 2 g of water was added to ensure uniform dispersion of the copper precursor solution in _SiO2 . The obtained wet solid was vacuum degassed at 120°C for 48 hours, dried at 120°C for 12 hours, and then calcined at 500°C for 3 hours. The Cu loading was 12 wt%.

0.5 g Cu/SiO ₂ (first catalyst layer) and 0.5 g H-MOR (second catalyst layer) obtained from TOSOH, Japan were placed in a stainless steel reactor with an inner diameter of 9.5 mm. The distance between the Cu/SiO ₂ catalyst layer and the H-MOR was 1 cm, and quartz wool was used for isolation.

Catalyst activity test

Before exposure to the reactants, the catalyst was pretreated in flowing 20 mL/min high purity _H2 at 400°C for 3 hours. The reaction was carried out at 2.0 MPa and a constant temperature of 220°C, with the reaction gas Ar/DME/CO (3.1 mol% Ar, 5.2 mol% DME, the balance CO, obtained from Sumitomo Chemical) flowing through the catalyst layer at a flow rate of 20 mL/min.

Example 2

The procedure of Example 1 was repeated, except that the copper content of the Cu(NO ₃ ) ₂ ·3H ₂ O aqueous solution was 1.14 g Cu(NO ₃ ) ₂ ·3H ₂ O, thereby preparing Cu/SiO ₂ with a Cu loading of 6 wt %.

Example 3

The procedure of Example 1 was repeated, except that the copper content of the Cu(NO ₃ ) ₂ ·3H ₂ O aqueous solution was 0.57 g Cu(NO ₃ ) ₂ ·3H ₂ O, thereby preparing Cu/SiO ₂ with a Cu loading of 3 wt %.

Example 4

The procedure of Example 1 was repeated, except that the copper content of the Cu(NO ₃ ) ₂ ·3H ₂ O aqueous solution was 0.29 g Cu(NO ₃ ) ₂ ·3H ₂ O, thereby preparing Cu/SiO ₂ with a Cu loading of 1.5 wt %.

Example 5

The procedure of Example 1 was repeated, except that the copper content of the Cu(NO ₃ ) ₂ ·3H ₂ O aqueous solution was 0.15 g Cu(NO ₃ ) ₂ ·3H ₂ O, thereby preparing Cu/SiO ₂ with a Cu loading of 0.75 wt %.

Example 6

The procedure of Example 1 was repeated, except that the copper content of the Cu(NO ₃ ) ₂ ·3H ₂ O aqueous solution was 0.11 g Cu(NO ₃ ) ₂ ·3H ₂ O, thereby preparing Cu/SiO ₂ with a Cu loading of 0.6 wt %.

Example 7

The procedure of Example 1 was repeated except that 10 mL of an aqueous solution containing 1.48 g of Pd(NO ₃ ) ₂ was used to prepare Pd/SiO ₂ with a Pd loading of 12 wt %.

Example 8

The procedure of Example 1 was repeated, except that 0.5 g of H-type ZSM-34 (second catalyst layer) synthesized by the method of DOI https://doi.org/10.1039/C2JM31479G literature was used instead of H-MOR.

Example 9

The procedure of Example 1 was repeated except that 0.5 g of H-CHA (second catalyst layer) from Clariant was used instead of H-MOR.

Comparative Example 1

Only H-MOR was used as catalyst.

Comparative Example 2

The same as Example 1, except that H-MOR is used as the first catalyst layer, and Cu/ _SiO2 prepared in Example 1 is used as the second catalyst layer.

Comparative Example 3

The same as Example 1, except that only Cu-MOR was used as the catalyst. The preparation of Cu-MOR was the same as Example 1, except that H-MOR was used instead of SiO ₂ used therein.

Comparative Example 4

Same as Example 1, except that Cu/ _SiO2 and H-MOR were physically mixed and then used as catalyst.

The space-time yield and selectivity of methyl acetate for each catalyst were determined. The results are summarized in Table 1.

Table 1

As can be seen from Table 1, the catalyst of the present invention has a significantly improved space-time yield of methyl acetate and has considerable selectivity. Compared with Comparative Example 1 using pure H-MOR, the space-time yield of methyl acetate of the catalyst of the present invention is increased by up to 170%.

Claims

A catalyst comprises a first catalyst layer comprising a metal supported on a support material and a second catalyst layer comprising an H-type molecular sieve, wherein the first catalyst layer and the second catalyst layer are spatially isolated.
The catalyst as claimed in claim 1, wherein the metal in the first catalyst layer is one or more of Ca, Ag, Ce, Pt, Pd, Ga, Zn, Mg, Au, Co, Fe, Zr, Ni or Cu, preferably one or more of Cu, Pd, Ag, Ce, Co, Ga, Zr, Zn or Fe, most preferably one or both of Cu or Pd.
The catalyst as claimed in claim 1 or 2, wherein the support material in the first catalyst layer is silicon dioxide, zirconium oxide, titanium dioxide, ceria, activated carbon, graphene, carbon nanotubes or a combination thereof, preferably silicon dioxide, activated carbon, graphene, carbon nanotubes or a combination thereof.
The catalyst according to any one of claims 1 to 3, wherein the H-type molecular sieve is H-type ZSM-34, ZSM-35, MOR, CHA, OFF, EU-12, Al-RUB-41 or HSUZ-4, preferably H-type OFF, EU-12, Al-RUB-41, ZSM-34 or MOR, more preferably H-MOR.
The catalyst according to any one of claims 1 to 4, wherein the metal loading of the support material in the first catalyst layer is 0.001 to 30% by weight, preferably 0.01 to 25% by weight, more preferably 0.1 to 20% by weight, most preferably 0.5 to 15% by weight, in each case based on the total weight of metal and support material.
The catalyst according to any one of claims 1 to 5, wherein the first catalyst layer and the second catalyst are spatially separated by a distance of 0.5-100 cm, preferably 1-100 cm, more preferably 1-50 cm, more preferably 1-20 cm, most preferably 1-10 cm.
A method for preparing methyl acetate by carbonylation of dimethyl ether and/or methanol, wherein the catalyst according to any one of claims 1 to 6 is used.